You are visiting a farm that has a single row of fruit trees arranged from left to right. The trees are represented by an integer array fruits where fruits[i] is the type of fruit the ith tree produces. You want to collect as much fruit as possible.

totalFruit.js

/**
 * @param {number[]} fruits
 * @return {number}
 */
var totalFruit = function(fruits) {
    let maxFruits = 0;
    let left = 0;
    const basket = new Map(); // Holds fruit type and count

    // Move the right boundary of the window
    for (let right = 0; right < fruits.length; right++) {
        const fruit = fruits[right];

        // Add current fruit to the basket (or update count)
        basket.set(fruit, (basket.get(fruit) || 0) + 1);

        // If we have more than two fruit types, shrink from the left
        while (basket.size > 2) {
            const leftFruit = fruits[left];
            basket.set(leftFruit, basket.get(leftFruit) - 1);
            if (basket.get(leftFruit,) === 0) {
                basket.delete(leftFruit); // Remove when count hits zero
            }
            left++; // Move window's left side
        }

        // Update max fruits picked in a valid window
        maxFruits = Math.max(maxFruits, right - left + 1);
    }

    return maxFruits;
};